Human powered vehicles, such as bicycles, typically rely on a crank set having a pair of crank arms that fully revolve 360xc2x0. Thus, for optimal performance, the crank-arm length has to be formulated based on the human propelling engine, i.e., legs or arms. In this respect, after much studies and debate, for leg-powered cranks, the crank-arm length has been typically formulated to less than eight inches. Indeed, commercial bicycle crank arms sold have an effective length of 165 to 180 mm, in increments of 5 mm.
The revolving crank design, however, is not believed to be the optimal way of propelling human powered vehicles. Accordingly, this inspired various proposed crank designs, including an oscillation type using longer crank arms. None have yet made through commercially.
There remains a need for alternative ways of propelling human powered vehicles. The present invention addresses this need.
The present invention relates to a human powered vehicle and a propelling mechanism thereof, which uses an oscillating crank type.
One aspect of the present invention is a human propelled vehicle, which can be, for instance, a bicycle. The vehicle can have a frame, at least one front wheel attached to the frame, at least one back wheel attached to the frame, a power transmission mounted to the frame for driving at least one of the wheels, and a propelling mechanism attached to the frame or have a mounting structure, such as a housing, that is integrally formed with the frame.
Another aspect of the present invention is the propelling mechanism for the vehicle mentioned above. The propelling mechanism can include a gearbox housing, first and second input shafts, first and second crank arms, a gear train, a conversion mechanism, and an output shaft. The first and second input shafts, and the output shaft can be rotatably journaled or mounted to the housing. The first crank arm can be secured to the first input shaft from one side of the housing and the second crank arm can be secured to the second input shaft from the opposite side of the housing.
Each of the first and second crank arms can have a length greater than eight inches. In this respect, an effective length of each crank arm can be between 8-14 inches. Also, the crank arm can be adjustable in length so that its effective length is adjustable between this range. The first and second crank arms can extend rearwardly from the respective first and second shafts so that the first and second crank arms can reciprocate in the opposite directions through an arc that passes behind the bottom bracket axle or the bottom bracket 13.
The gear train can include first and second gears mounted on the first input shaft, third and fourth gears mounted on the second input shaft. The first gear can engage the third gear so that the first and second crank arms can pivot in opposite directions. The conversion mechanism can be trained or coupled with the second and fourth gears for converting the reciprocating pivoting movements of the second and fourth gears driven by the first and second crank arms into a unidirectional rotation. The output shaft can be trained or coupled with the conversion mechanism and coupled to the power transmission for driving the one wheel, which can be either the front or the rear wheel.
In one embodiment, the frame can be a bicycle frame having a bottom bracket. The power transmission can include an axle rotatably journaled to the bottom bracket. The gearbox housing can be mounted to the frame so that it is located in front of the bottom bracket. The bicycle frame can further have a head tube and a down tube interconnecting the head tube and the bottom bracket. The gearbox housing can be removably attached or mounted to the down tube so that the entire housing is located in front of the bottom bracket.
The power transmission can include a drive sprocket secured to the output shaft on one outer side of the gearbox housing, a first driven sprocket secured to the bottom bracket axle on the same side of the gearbox housing as the drive sprocket, and a first chain training or coupling the drive sprocket and the driven sprocket. The power transmission can further include at least one second driven sprocket secured to the bottom bracket axle on the opposite side of the first driven sprocket, at least one wheel sprocket mounted to the one wheel, and a second chain training or coupling the second driven sprocket and the wheel sprocket.
The first and second input shafts and the bottom bracket axle all can be mounted parallel to the housing, but the first and second input shafts can be offset one above the other so that the distance between the first input shaft and the bottom bracket axle or the bottom bracket is the same as the distance between the second input shaft and the bottom bracket axle or the bottom bracket.
The conversion mechanism can include a third shaft rotatably journaled to the gearbox housing, and first and second free-wheeled gears mounted on the third shaft. The first and second freewheeled gears can respectively engage the second and fourth gears so that they can rotate the third shaft in one direction, but allow them to freely rotate in the opposite direction without rotating the third shaft in the same direction. The conversion mechanism can further include a fifth gear mounted on the third shaft, a fourth shaft rotatably journaled to the housing, sixth and seventh gears mounted on the fourth shaft, and an eighth gear mounted to the output shaft. The fifth gear can engage the sixth gear to drive the fourth shaft, and the seventh gear can engage the eighth gear to drive the output shaft. In another embodiment, the sixth gear can be omitted. Instead, the fourth shaft only has an intermediary or seventh gear, which can engage the output or eighth gear on the output shaft.
The first and second gears can be integrally united together or formed together and the third and fourth gears can be united together or formed together. The first and third gears can be positioned between the second and fourth gears. One of the fifth, sixth, seventh (intermediary), and eighth (output) gears can be freewheeled so that the output shaft does not back drive either the third or fourth shaft when the output shaft is rotated in reverse to the propelling direction. In one embodiment, the seventh gear is freewheeled so that the output shaft does not back drive the fourth shaft.
The propelling mechanism can further include means for mounting at least one of the first and second crank arms offset from the respective shaft. The propelling mechanism can further include an angular adjustment mechanism for angularly adjusting at least one of the first and second crank arms relative to the respective first or second shaft. The angular adjustment mechanism can include a first disk secured to one of the first and second input shafts. The angular adjustment mechanism can further include a second disk secured to the other of the first and second input shafts for a greater adjustment capability. The first and second disks can be secured respectively to the first and second input shafts. The first and second crank arms can be adjustably secured respectively to the first and second disks. The first and second disks can each have a plurality of positioning holes. The first and second crank arms can be mounted to the respective disks through at least a pair of diametrically opposing positioning holes.
Each of the first and second disks can have inner and outer concentric circular arrays of positioning holes, and each of the first and second crank arms can have two pairs of holes, one pair for mounting to the inner circular array of positioning holes and the other pair for mounting to the outer circular array of positioning holes.
The number of positioning holes in each of the first and second disks, for example, can be 36 or 40. For 36 and 40 hole disks, each circular array of positioning holes can have 18 or 20 position holes, which can be equally spaced. The positioning holes of the inner circular array can be circumferentially staggered relative to the positioning holes of the outer circular array. The positioning holes of each of the inner and outer circular arrays can be spaced at 20xc2x0 and 18xc2x0 intervals, and the spacing between adjacent holes of the staggered positioning holes can be spaced at 10xc2x0 and 9xc2x0 intervals for the 36 and 40 hole disks, respectively.
Each of the first and second disks also can have a hexagonal hole, and the respective first or second input shaft can have a hexagonal end that mates with the hexagonal hole. The hexagonal hole allows a quick 60xc2x0 shift interval of the respective disk relative to the respective shaft.
The propelling mechanism can further include a stop for limiting the pivoting movement of each crank arm. The bicycle frame can further include a seat tube extending from the bottom bracket, at which the stop can be mounted. The stop also can be mounted to the gearbox housing or underneath the same.
The propelling mechanism or the gearbox housing further includes an anti-theft ring for attaching an anti-theft device. The gearbox housing can be mounted to the down tube with at least two U-bolt.